Airborne Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Hospitals: Effects of Aerosol-Generating Procedures, HEPA-Filtration Units, Patient Viral Load, and Physical Distance. (28th February 2022)

• Record Type: Journal Article
• Authors: Thuresson, Sara; Fraenkel, Carl Johan; Sasinovich, Sviataslau; Soldemyr, Jonathan; Widell, Anders; Medstrand, Patrik; Alsved, Malin; Löndahl, Jakob
• Is Part Of: Clinical infectious diseases. Volume 75:Number 1(2022)
• Page Start: e89
• Page End: e96
• Publication Date: 2022-02-28
• Subjects: virus transmission -- aerosol-generating procedures -- infection control -- inhalation exposure; Communicable diseases -- Periodicals; 616.905
• DOI: 10.1093/cid/ciac161
• Languages: English
• ISSNs: 1058-4838

Abstract

Abstract: Background: Transmission of coronavirus disease 2019 (COVID-19) can occur through inhalation of fine droplets or aerosols containing infectious virus. The objective of this study was to identify situations, patient characteristics, environmental parameters, and aerosol-generating procedures (AGPs) associated with airborne severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Methods: Air samples were collected near hospitalized COVID-19 patients and analyzed by RT-qPCR. Results were related to distance to the patient, most recent patient diagnostic PCR cycle threshold (Ct) value, room ventilation, and ongoing potential AGPs. Results: In total, 310 air samples were collected; of these, 26 (8%) were positive for SARS-CoV-2. Of the 231 samples from patient rooms, 22 (10%) were positive for SARS-CoV-2. Positive air samples were associated with a low patient Ct value (OR, 5.0 for Ct <25 vs >25; P = .01; 95% CI: 1.18–29.5) and a shorter physical distance to the patient (OR, 2.0 for every meter closer to the patient; P = .05; 95% CI: 1.0–3.8). A mobile HEPA-filtration unit in the room decreased the proportion of positive samples (OR, .3; P = .02; 95% CI: .12–.98). No association was observed between SARS-CoV-2–positive air samples and mechanical ventilation, high-flow nasal cannula, nebulizer treatment, or noninvasive ventilation. An association was found with positive expiratory pressure training ( P < .01) and a trend towards an association for airway manipulation, including bronchoscopies and in- and extubations. Conclusions: Our results show that major risk factors for airborne SARS-CoV-2 include short physical distance, high patient viral load, and poor room ventilation. AGPs, as traditionally defined, seem to be of secondary importance. Abstract : Healthcare infection-control guidelines emphasize breathing protection during aerosol-generating procedures with COVID-19 patients. Our study suggests that SARS-CoV-2 in air is mainly determined by distance, patient viral load, and room ventilation. We found weak support for emissions during aerosol-generating procedures.